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From
the Porsche “Technical Specifications” booklet available from 928 Specialists.
928 S4 page
|
Testing and Adjusting Specifications
Model year
Engine type
|
Mod. 87 …89
M 28.41/42
|
Mod. 89
M 28/47
|
Test Point
|
Specifications
|
Specifications
|
Electric
fuel pump Delivery rate
|
at
least
1250
cm3/30s
|
at
least
1250
cm3/30s
|
Fuel pressure (engine stopped)
Fuel
pump relay bridged
|
3.8
±
0.2 bar
|
3.8
±
0.2 bar
|
Check
value for idle
|
approx.
3.3 bar
|
approx.
3.3 bar
|
Leak
test
Min.
pressure after 20 min.
|
3.0
bar
|
3.0
bar
|
|
M 28.41/42
|
M 28/47
|
Idle setting
|
without catalytic converter
|
with converter
|
without catalytic converter
|
with converter
|
Idle
speed (rpm)
|
675
± 25
|
675
± 25
|
775
± 25
|
775
± 25
|
CO
level %
|
0.5…1.5
|
0.4…1.2
|
0.5…1.5
|
0.4…1.2
|
HC-levels
ppm
|
<300
|
<300
|
<300
|
<300
|
|